Fully Oxide-based Zero-Emission and Portable Energy Supply

Project Information

FOXES

Grant agreement ID: 951774

DOI

10.3030/951774

Project closed

EC signature date 6 July 2020

Start date 1 October 2020

End date 31 March 2025

Funded under

• EXCELLENT SCIENCE - Future and Emerging Technologies (FET)

Total cost

€ 3 992 100,00

EU contribution

€ 3 992 100,00

Coordinated by

MATERIALS CENTER LEOBEN FORSCHUNG GMBH
Austria

Periodic Reporting for period 3 - FOXES (Fully Oxide-based Zero-Emission and Portable Energy Supply)

Reporting period: 2023-10-01 to 2025-03-31

Summary of the context and overall objectives of the project

The overall objective of FOXES was the realization of a radically new paradigm for providing power generation for energy autonomous applications in sensor networks and IoT devices. In detail the objectives were to develop the key components of the power cube and the sensor node:

• Lead-free perovskite solar cell (PSC) with energy efficiency of at least 10%, and 6 µW/cm2 energy generation by indoor lighting conditions (400 lux)
• Lead-free perovskite multilayer Thin Film Capacitor (TFC) with energy density > 50 J/cm3
• Energy Management Circuit (EMC) to charge the capacitor with the PSC energy
• Development of process route for 3D integration of PSC, TFC and EMC
• Light-activated semiconductor gas sensor (SGS) for a sensor node requiring less than 50 µW.

BUW successfully developed organic solar cells (OSC) that can deliver 122 µW/cm2 under 400 lux illumination, which is enough power for the Power Cube and the demonstrator. A semi-dry transfer process for 2D materials such as graphene and hBN has been developed by AMO, which is key for thermal dissipation in solar cell devices. TFCs based on BaZrTiO3 (BZT) have been realized with maximum recoverable energy density of 32.4 Jcm-3. An EMC based on oxide thin-film transistors (TFT) has been realized by UNINOVA along with new interconnectivity schemes. UB developed an ultra-low-power IoT node for gas-sensing applications, based on light-activated SGS and a full-custom CMOS design.
The consortium finally developed the 9.6 × 9.6 cm2 sized FOXES demonstrator (Fig.1) which was deployed in three different real-world environments in the city of Barcelona. The FOXES consortium successfully validated the feasibility of a sub-50 µW fully integrated sensor node employing the optimized light-activated gas sensor.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

BUW successfully fabricated lead-free perovskite materials with band gaps aiming for tandem applications and achieved power conversion efficiencies of 5 %. In parallel an ultra-thin ALD grown InOx interconnecting layer for tandem solar cells was realized, which sets a new world record (published: Nature volume 604, pp. 280-286 (2022)). The developed organic non-fullerene acceptor solar cells meet the stability target of 1000 h, and generate a power of 26 µW under 400 lux illumination fulfilling the project specifications of 6 µW/cm2.

AMO successfully developed a low-temperature, semi-dry transfer process for 2D materials that is fully compatible with humidity- and temperature-sensitive materials both all-inorganic and hybrid organic–inorganic variants. This technique enables the reliable integration of various 2D materials, including graphene, hexagonal boron nitride, and molybdenum disulfide, onto perovskites with different dimensionalities (3D, 2D, and 0D).

MCL successfully realized lead-free perovskite TFCs based on BaZrxTi1-xO3 (BZT, x = Zr-content) films, which were fabricated by a Chemical Solution Deposition (CSD) process on Pt/Si substrates. The BZT films have been systematically optimized by variation of the Zr-content, where all produced thin films were fully characterized regarding their electrical properties. We found that the best-performing composition is BZT15 with a high recoverable energy density of 32.4 Jcm-3. This value, despite being lower than the targeted 50 Jcm-3, is a highly remarkable result.

UNOVA successfully developed miniaturized oxide thin-film transistors (TFT) EMCs based on oxide TFTs. Devices with channel length of 0.6 µm have been realized which meet the required operational frequency of 300 MHz. The final EMC with dimensions of 2.13 x 2.18 mm² can deliver three fixed output voltages, 1.2 V, 1.8 V, and 3.3 V, independent of the input voltage (VIN) from the solar cell. The achieved power dissipation was 6.40 mW for a VIN of 6 V, which is a decrease of 88% as compared to the first version.

UB fully integrated the FOXES demonstrator achieving the main objective of the project: the development of a gas sensor integrated in a sensor node consuming less than 50 µW to control light excitation, acquire sensor data, and transmit it wirelessly. The final demonstrator was deployed in three different real-world urban locations in Barcelona: The faculty’s patio, a window-lit outdoor environment, and a rooftop exposed to full sunlight. In all cases, the system demonstrated fully autonomous operation, adapting acquisition and transmission rates to the available energy. Integrated into the IoT Bundle, the system operated autonomously for over 6 hours under 400 lux illumination using solar energy stored in a supercapacitor, with an average consumption of approximately 12 µW. The FOXES the project has successfully met all its technical goals and delivered a validated, energy-autonomous sensor node based on flexible and low-power technologies.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

BUW developed a novel ultra-thin ALD grown InOx interconnecting layer for tandem solar cells with unprecedented optical and electronic properties, that can be applied for lossless transfer charges from one sub-cell into the other. BUW was able to set a new milestone for perovskite-organic tandem devices, which is now also notified in the NREL “Best Research-Cell Efficiency” chart (https://www.nrel.gov/pv/cell-efficiency).

AMO managed to directly transfer centimeter-scale, large-area 2D materials onto all types of perovskites—including both all-inorganic and hybrid organic – inorganic perovskites - for the first time. The developed semi-dry transfer method enables the use of 2D materials to enhance various perovskite optoelectronic devices, such as solar cells, light-emitting diodes, laser diodes, and photodetectors.

MCL successfully developed a novel aqueous CSD process for the fabrication of BZT-based TFCs, and highly conductive RuO2, LaNiO3, and SrRuO3 metal oxide films. All experimental parameters, have been optimized to yield high quality thin films which meet the initial goals of the project. As compared to sputtering technologies, which require pre-fabricated sputter targets, CSD provides high flexibility in terms of material variation, which is key for device optimization. An upscaling approach is presently evaluated with companies in detail regarding feasibility, robustness, and costs.

UNOVA could demonstrate significant advances in innovative interconnectivity schemes based on printing that enable an easy and universal integration of rigid or flexible components onto a receiving substrate, such as a PCB. These strategies go well beyond current state of the art and allow to replace traditional processes like wire bonding, which requires thick metallization pads that typically are not compatible with flexible electronics components.

UB successfully achieved ultra-low power features in different chip design domains, including wake-up timers, current DACs, resistance measurement oscillation circuits, and signal acquisition chains. These blocks enable full sensor node operation within strict power constraints and contribute to the system-level objective of sub-50 µW operation. Sensor chips developed at UB also display record power consumption values, both for illuminated gas sensors and for colorimetric sensing modules.
The FOXES results open the path to new classes of low-cost and environmentally sustainable sensor nodes, with potential impact in applications such as indoor air quality monitoring, smart packaging, and disposable diagnostics.

Fig.2 - FOXES demonstrator deployment scenario 1_faculty's patio

Fig.1 - Final FOXES Demonstrator

Fig.4 - FOXES demonstrator deployment scenario 3_rooftop

Fig.3 - FOXES demonstrator deployment scenario 2_flat level